The present disclosure relates to a cooling device anomaly diagnosing apparatus that is adapted for a cooling device in an internal combustion engine. In particular, the cooling device includes: an inner channel serving as a cooling channel located inside the internal combustion engine; an outer channel serving as a cooling channel located outside the internal combustion engine, the outer channel constituting, together with the inner channel, a loop path in which cooling water is circulated; and a regulating device capable of adjusting the cross-sectional area of the flow passage between the inner channel and the outer channel by an electronic control. The regulating device includes a check valve configured to open when a pressure inside is higher than a pressure in the outer channel by an amount greater than or equal to a predetermined amount.
For example, Japanese Patent Laid-Open No. 2017-67045 discloses a multi-way valve (regulating device) with a check valve. The check valve is capable of adjusting the cross-sectional area of a flow passage between a cooling channel located inside the internal combustion engine and a cooling channel located outside the engine by an electronic control and is configured to open when the pressure inside is higher than the pressure in the outside cooling channel by an amount greater than or equal to a predetermined amount.